Download The foot

The foot
• The foot – bony architecture, muscles, how it can be both pliable to
walk on rough ground but also act as a solid lever at push off
• The importance of the arches of the foot
• The foot in normal gait and posture and its influence in abnormal
alignment of the lower limb
• Common conditions – hallux valgus (bunions), heel pain, hammer
toes, plantar fasciitis
Extreme functions of the foot
Propulsion to jump
Balance and propulsion for stairs
From ballet dancer to elite athlete
• 3 main functions
• Weight transmission of the body weight to the ground in
walking
• Balance – maintains equilibrium of posture when walking and
jogging
• Assistance in ambulation – propulsion to move the body
forwards during walking
• It has to be both pliable to accommodate to rough ground
and rigid in propulsion so that energy is utilised efficiently to
propel the body forwards
• The toes are designed to give a wider base for balance and
for propulsion
The bones of the foot
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Hind foot - talus and calcaneus
Mid foot - navicular, cuboid and 3 cuneiform bones
Forefoot – 5 metatarsals and the phalanges
Note the ‘S’ shaped joint line between the talonavicular
joint and the calcaneocuboid joint – important later
• The base of the 2nd metatarsal sits in a mortice between
the 1st and 3rd metatarsals and the cuneiforms – this
can cause problems if the 2nd toe is longer than the first
leading to stress #’s of the base of the metatarsal –
March #
Lateral view of the foot
• Lateral arch of the foot consists of the
calcaneus, cuboid and 5th metatarsal
• The shape of the bones, ligaments and
tendons, particularly peroneus longus,
give support
Ligaments of the lateral aspect of the foot
• Dorsal ligaments between bones of the midfoot
and the metatarsals
• Y shaped bifurcate ligament – calcaneocuboid
and calcaneonavicular
• Long plantar ligament – supporting the
longitudinal arches of the foot
• Note peroneus brevis tendon inserting onto the
base of the 5th metatarsal
Medial view of the foot
• The medial arch of the foot is comprised of
the calcaneus, navicular, medial cuneiform,
and 1st metatarsal
• The bony arch is maintained partly by the
shape of the bones
• The navicular is considered to be the
keystone of the arch
• The arch is also supported by the tendons of
tibialis posterior and flexor hallucis longus
Ligaments of the medial aspect of the foot
• Note the deltoid ligament of the ankle
• Spring ligament – from the sustentaculum tali –
a bony protuberance on the calcaneus to the
navicular
• This ligament is crucial in supporting the head
of the talus as it articulates with the navicular
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arch of the foot
Ligaments of the forefoot
• Metatarsophalangeal joints (MTP) – and
interphalangeal joints have collateral ligaments
• The heads of the metatarsals are held together by the
deep transverse metatarsal ligament and by muscles (Cf
later)
Roman arch
• Bony structure of the arches of the foot likened
to a Roman arch
Any questions
Layers of muscles in the sole of the foot
Plantar aponeurosis
• Plantar aponeurosis – made of dense fascia consisting of white
fibres. It has great strength
• It starts from the calcaneus and spans the sole of the foot inserting
into the proximal phalanx of each toe
• When the toes are extended the longitudinal arch of the foot is
raised through the windlass effect as the fascia is tensioned and
pulls the calcaneus closer to the toes
• Intrinsic muscles
• Extend from the calcaneus to the
toes
• Assist in maintaining the concavity
of the foot and flexing the toes
• The tendons of flexor digitorum
brevis insert into the intermediate
phalanx of the 2nd to 5th toes
• Abductor hallucis – originates from
the calcaneus and inserts into the
medial side of the base of the
proximal phalanx of the big toe
• The muscle is activated when
spreading the toes
• Abductor digiti minimi – from the
calcaneus to the outside of the
base of the proximal phalanx of
the 5th toe
• Active when spreading the toes
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Layer of intrinsic muscles
• Lumbricals – 4 small muscles accessory to the
tendons of flexor digitorum longus
• They arise from the tendons of flexor digitorum
longus
• The tendons pass to the medial side of the 4
lesser toes and attach to the dorsal expansion (Cf
later)
• These muscles lift the heads of the metatarsals
along the transverse arch when they contract
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layer of muscle
• Flexor hallucis brevis – originates from a Y shaped
tendon from the cuboid and the lateral cuneiform
• The muscle divides into 2 bellies which insert onto each
side of the base of the proximal phalanx of the great toe
• There are sesamoid bones associated with the insertions
which act like pulleys to improve the line of pull
• Adductor hallucis – 2 heads oblique and transverse
• Oblique arises from the bases of the 2nd to 4th MTs
• Transverse from the ligaments of the 3rd to 5th toes
• The portions of the muscle are attached to the lateral
sesamoid and base of the first phalanx
• Contraction of the muscle adducts the big toe
• Flexor digiti minimi brevis – arises from the base of the
5th MT. Its tendon inserts into the lateral side of the
proximal phalanx of the 5th toe
• Contraction of the muscle flexes the little toe
• Dorsal and plantar interossei - 4 muscles
arising from the metatarsals
• 1st inserts on the medial aspect of the
proximal phalanx of the second toe
• Other 3 on lateral side of the 2nd to 4th
toes. They also insert into the dorsal
digital expansion (Cf later)
• 3 plantar interossei situated below the
MT, base of the 3rd – 5th MT
• Attached to the medial sides of the bases
of the proximal phalanges
• The dorsal interossei abduct the toes. The
plantar adduct the toes
The dorsal aspect of the foot
• Extensor digitorum brevis – arises from the
superior surface of the calcaneus. It extends
medially across the dorsum of the foot ending in
4 tendons
• The most medial portion of the muscle is
termed the extensor hallucis brevis, inserting
into the base of the proximal phalanx of the
great toe
• The other 3 tendons attach to the lateral side of
the tendons of extensor digitorum longus to the
2nd-4th toes
• Note the dorsalis pedis artery close to the
medial side of EHB – important indicator of
peripheral vascular disease if pulse absent
• Note the arrangement of the extensor hood
associated with each toe
Arrangement of the extensor tendon and
dorsal expansion
• Note the central slip of the extensor tendon to the
base of the intermediate phalanges
• The insertion of the lumbrical into the dorsal
expansion flexes the MTP joint whilst keeping the
toe straight – cupping the sole of the foot
The course of the tibial nerve
• The tibial nerve runs down the centre of
the posterior calf under the soleus muscle
• At the ankle it passes around the medial
malleolus
• A branch of the nerve supplies the back of
the heel – this can be involved in heel
pain
Medial and lateral plantar nerves
• The tibial nerve divides into medial and lateral plantar
nerves under the flexor retinaculum at the medial side of
the ankle
• In the foot the medial plantar nerve lies between the
abductor hallucis and flexor digitorum brevis
• It further divides into digital branches which supply the
medial 3 ½ toes
• The lateral plantar nerve supplies the lateral 1 ½ toes
• Nerves are vulnerable where they divide so pain over the
instep can sometimes be related to compression or
irritation of the nerve
• The digital nerves can also be problematic (Cf later)
The talocalcaneonavicular joint
• The talus acts like a ball bearing between the ankle, the
calcaneus below and the navicular in front
• The axis of the joint is inclined upwards 40 degrees and
30 degrees medially
• The bones and joints forwards of the TCN joint form a
single elastic unit which move in response to
movement of the talus and calcaneus
• The transverse tarsal joint includes the calcaneocuboid
joint
• Form and ‘S’ shaped joint line
• When the foot is weight bearing there is relatively little
movement between the naviculo-cuboid unit
• As the TCN joint supinates the shape of the joint
surfaces and ligaments pulls the transverse tarsal joint
into a locked position to form a rigid lever for
propulsion
The midtarsal joint during pronation
Summary of movements at the ankle,
subtalar and midfoot
• Inward ( medial) rotation of the tibia and talus,
everts the heel via the subtalar joint which in turn
causes the midfoot to pronate or the medial arch to
flatten
• In order for the toes to remain in contact with the
ground the forefoot – tarsometatarsal joints
undergo a compensatory twist into supination
Visualising the foot as a twisted sheet of
paper
• The anterior margin runs along the line of the
heads of the metatarsals and is flat to the ground
• The posterior margin is vertical representing the
calcaneus
• The twist imposes arches of the foot
• Loading of the foot tends to flatten the arches
• Removal of body weight returns the arches
The foot and muscle activation during walking
Supination and pronation during walking
• Heel strike occurs along the lateral border of the heel,
therefore the foot is slightly supinated
• As the body weight transfers along the lateral border of
the foot the heel everts and the foot pronates to
become more flexible to accommodate to the surface of
the ground
• When the foot is flat on the ground the heel is in a
neutral position, as is the rest of the foot
• As the heel starts to lift at push off it inverts and the
midfoot and forefoot supinate to become a rigid lever
Running gait
• Running requires greater balance, muscle strength
and range of movement
• Greater balance because a lack of the double
support phase and a float phase when neither foot
is in contact with the ground
• As the speed of running increases so does the float
time
• Muscles generate greater energy as the head, arms
and trunk are raised higher than in normal gait
• Muscles and joint structures have to absorb more
energy
Running in shoes v running barefoot
Different types of foot strike during running
Pes Planus – flat foot
• Congenital flat foot – often raises concerns in children
but if the arch returns when non-weight bearing it is
not generally a problem
• Adult acquired flat foot deformity – related to
dysfunction of the tibialis posterior muscle and tendon
but can also be related to problems with the spring
ligament
• Tibialis posterior can be stretched or ruptured. Leaves
the primary and secondary everters of the foot, the
peroneus brevis and the peroneus longus, relatively
unopposed leading to flattening of the medial arch
• Obesity and diabetes can predispose the tendon to
rupture
• Traumatic rupture of the spring ligament or plantar
fascia can also lead to medial arch collapse
Consequences of a pronated foot
• Over pronation of the foot leads to relative leg
shortening and a valgus deformity at the knee
• This can tilt the pelvis downwards leading to side
flexion of the lumbar spine
• Lumbar spine side flexion tilts the shoulder girdle
down on the unaffected side
• The cervical spine side flexes in the opposite
direction to the lumbar spine to keep the eyes
level
Management
• Examination of the foot to determine whether the joints
of the foot are stiff, range of movement, muscle function
within the foot, in the calf, at the knee and hip, palpation
of tibialis posterior tendon to ascertain whether this is
the issue
• Use of an orthotic to correct the heel position and
support the medial arch
• Strengthening exercises at the hip to correct lower limb
alignment
• Offloading the tendon, not walking with bare feet, weight
loss
Plantar fasciitis
• Pain under the heel caused by over stretching of
the plantar fascia
• Caused by an over pronated foot
• A high arched foot (Cf later)
• Sudden increase in activity
• Obesity, pregnancy
• Poorly fitting shoes which do not support the foot
sufficiently
• Can be particularly painful first thing in the
morning, or after rest, as the plantar fascia has
contracted to its normal position
• Management – address the cause, over pronation –
use an orthotic, increase muscle function around
the hip
• Weight loss
• Wear a heel cup to cushion the heel, avoid running
on hard ground
Hallux valgus - Bunion
• Can be a genetic tendency
• Over pronation of the foot pushing the big toe out of
position
• Habitually wearing tight fitting, pointed shoes
• Inflammation of the bursa, arthritis of the 1st MTP joint
• Management – wear shoes with a deeper toe box,
Type of splint and spacer
• If the problem is mild a splint and spacer
between the first and second toes may help to
manage the symptoms
Surgical procedure to correct hallux valgus
• Correction of the position of the metatarsal
• In this example osteotomy of the phalanx to
achieve good alignment
Conditions affecting the toes
• Claw toe can affect any toe other than the big toe
• Caused by tightness of ligaments and tendons causing the
toe to flex
• A flexible claw toe can be corrected manually
• A rigid claw toe may be associated with arthritis
• Hammer toe – Flexed at the PIP joint due to muscle
imbalance – poor function of the lumbrical muscles
• Can affect any toe other than the big toe
• Mallet toe – the DIP joint becomes flexed pushing the toe
down into the sole if the shoe
• Can occur after toe fracture, stubbing the toe
• Management – various products to reduce pressure on
the toes
• Correct footwear with a deep toe box to reduce rubbing
• Intrinsic foot exercises, stretching of tight structures,
strengthening extrinsic muscles
• Surgical intervention
Metatarsalgia
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Pain over the heads of the metatarsals
Overuse such as running, jumping
Wearing high heeled shoes
Being overweight
Stiffness of the ankle increasing pressure
on the foot
Management
• Wearing flatter shoes
• Use of a metatarsal pad placed behind the heads of the
metatarsals
Morton’s metatarsalgia
• Swelling of the digital nerve as it passes between the
heads of the metatarsals
• Cause is unknown but thought to be due to wearing tight
shoes which compress the nerve
• Often described as feeling like a pebble under the base of
the toe
• Burning pain sometimes numbness
• May be relieved by changing footwear
• Sometimes requires surgery
Pes Cavus
• Higher arch than normal, excessive supination of the
foot
• Associated with metatarsalgia and claw toes or hammer
toes
• Tightness of the plantar fascia, and tendoachillies
• Orthotics may be helpful
• Stretching of tight structures
Next week
• Shoulder girdle and glenohumeral joint
• Anatomy with a focus on muscle function
• What can go wrong with the shoulder joint
• Conditions such as tendinitis, rotator cuff tears
• Management of these conditions